The invention relates to a grinding device. The grinding device comprises a base. A bearing frame is fixedly installed on the base; a main rail plate is installed on the bearing frame; a compound groove is formed in the main rail plate, and the two end surfaces of the compound groove are each provided with a row of track wheel teeth; the track wheel teeth are all engaged with travel path gears, the two travel path gears are engaged with each other and both connected with short shafts, the lower end of one short shaft is connected with a motor, and a motor frame is installed on the lower portion of the motor; and driving belts are installed on the upper portions of the short shafts and connected with delivery shafts correspondingly, and the upper ends of the delivery shafts are connected with grinding discs correspondingly. According to the grinding device, by means of a wheel tooth driving mode, the two grinding discs are driven to constantly rotate, and the two grinding discs are driven to travel along the track of the compound groove, so that the lower end surface of a boss type part can be fully, uniformly and one time ground, and the grinding effect is are good.